Sunshine Butterflies - Attachment D - 010816-2

                                OUR BACKYARD
                                468 MCKINNON DRIVE, COOROIBAH

5.0       SUBSURFACE INVESTIGATION FINDINGS
5.1       Regional Geology
The 1:100,000 scale Gympie Special Geological Map (Sheet 9445 and Part 9545) indicates that the site is
underlain by deeply weathered sedimentary rocks of the Tiaro Coal Measures.

5.2       Subsurface Conditions
The subsurface conditions encountered in the boreholes were relatively consistent and comprised:

        Mostly loose to medium dense natural silty/clayey sands to between 0.3 m and 0.7 m BGL; overlying
        Stiff to very stiff silty or sandy clay of high plasticity to the depth of investigation.
Gravel and minor sand fill was intersected from the surface to depths of 0.05 m to 0.25 m BGL in boreholes
BH3, BH4, BH6 and BH7. Dense roadbase gravel was encountered to depths of 0.5 m and 0.2 m in
boreholes BH8A and BH8B, respectively. Possible cement treated base (CTB) was found at drilling refusal
depth of 0.2 m BGL in borehole BH8B.

Groundwater seepage was not encountered in any of the boreholes. It should be noted that groundwater
may develop, particularly as ‘perched’ seepage in the sands above the clay, following periods of heavy or
prolonged rainfall.

Detailed descriptions of the subsurface conditions encountered in the boreholes are provided in the borehole
logs in Appendix A, along with definition sheets which describe terms and abbreviations used on the logs.

5.3       Laboratory Test Results
The following Table 1 summarises the results of laboratory testing conducted on soil samples recovered from
the boreholes. Full test results (laboratory certificates) are presented in Appendix B.
Table 1: Summary of Laboratory Results
                                              Shrink-Swell
        BH No.            Depth (m)                                    CBR (%)                Swell (%)
                                               Index (%)

         BH1                0.45-0.73              3.2                     *                          *
         BH6                 0.3-0.55               *                     3.0                        3.2
         BH7                0.25-0.5                 *                   25.0                    -0.1
* denotes not tested

The laboratory test results indicate that the high plasticity silty clay samples from boreholes BH1 and BH6
have a relatively moderate to high potential reactivity to normal soil moisture changes.

CBR testing was conducted on samples of high plasticity silty clay (borehole BH6) and clayey silty sand
(BH7), with CBR values of 3.0% and 25.0% recorded, respectively. These values are in line with
expectations for such materials. It is noted that the CBR tests recorded variable swell values, being 3.2%
and -0.1%, which is expected to be due to the high clay and sand contents, respectively.




4 May 2016
Report No. 16081-001-Rev0                                   5